1. Technical Field
The present invention relates to a magnetic head apparatus having a magnetic head slider equipped with a magnetic element for performing a read and/or write operation from and/or into a magnetic disk and also relates to a magnetic disk apparatus equipped with the magnetic head apparatus. More particularly, the present invention relates to a magnetic head apparatus that changes in pitch angles of the magnetic head slider at the moment when it is just levitated from the magnetic disk and also varies the pitch angle due to a pressure change to prevent damage to the magnetic element and to stabilize the levitation attitude of the magnetic head slider. The present invention also relates to a magnetic disk apparatus equipped with the magnetic head apparatus.
2. Description of the Related Art
FIGS. 21 to 23 are plan views schematically illustrating disk-facing surfaces of magnetic head sliders disclosed respectively in Japanese Unexamined Patent Application Publications Nos. 2001-283549, 9-153210, and 2002-230732.
A magnetic head slider M1 shown in FIG. 21 has a step surface A, positive-pressure generating surfaces B, and a indented surface C formed on the disk-facing surface thereof. The step surface A and the positive-pressure generating surfaces B are formed so as to extend higher than the indented surface C, and also the positive-pressure generating surfaces B are formed so as to extend higher than the step surface A. The step surface A is formed so as to have a wide area extending toward a leading-side end surface S1 of the magnetic head slider M1. The positive-pressure generating surfaces B are formed closer to a trailing-side end surface St than the step surface A. The positive-pressure generating surfaces B are divided into two parts in the width direction (in the X direction indicated in the figure) and a step surface A1 resides therebetween. The surfaces B are formed integrally with and extend from the step surface A, which lies closer to the leading-side end surface S1 than the positive-pressure generating surfaces B.
The indented surface C is formed closer to the trailing-side end surface St than positive-pressure generating surfaces B and the step surface A.
As shown in FIG. 21, the magnetic head slider M1 has a magnetic element disposed close to the trailing-side end surface St. The magnetic element performs a read and/or write operation from and/or into a magnetic disk. The magnetic element is exposed to the disk-facing surface. The magnetic head slider M1 has a magnetic-element-facing surface E having the magnetic element disposed therein and extending so as to be flush with the positive-pressure generating surfaces B.
In contrast to the structure of the magnetic head slider M1 shown in FIG. 21, a magnetic head slider M2 shown in FIG. 22 has a structure in which the positive-pressure generating surface B is formed so as to extend long in the width direction (in the X direction indicated in the figure) and is not divided into two parts. As shown in FIG. 22, the magnetic head slider M2 has two positive-pressure generating surfaces B1 formed closer to the trailing-side end surface St than the positive-pressure generating surface B so as to be separated away from each other in the width direction (in the X direction indicated in the figure). The positive-pressure generating surfaces B1 and the positive-pressure generating surface B are connected to each other, in the longitudinal direction (in the Y direction indicated in the figure), with connecting surfaces A2 formed so as to be flush with the step surface A.
In contrast to the structure of the magnetic head slider M2 shown in FIG. 22, a magnetic head slider M3 shown in FIG. 23 has a structure in which the magnetic-element-forming surface E is formed so as to extend in the width direction (in the X direction indicated in the figure), and the indented surface C is interposed between the positive-pressure generating surface B and the magnetic-element-forming surface E.
In any of the magnetic head sliders M1, M2, and M3 shown in FIGS. 21 to 23, with rotation of a magnetic disk, air from the leading-side end surface S1 and flows below the step surface A and is compressed between the magnetic disk and the positive-pressure generating surface(s) B so as to generate a positive pressure, whereby a portion of the magnetic head slider extending close to the leading-side end surface S1 is raised more upward from the magnetic disk than another portion thereof extending close to the trailing-side end surface St. In addition, when the rotating speed of the magnetic disk increases, the magnetic head slider is levitated from the magnetic disk. In the levitated state, the magnetic element of the magnetic head slider maintains its inclination attitude so as to lie close to the surface of the magnetic surface while keeping an appropriate balance between positive and negative pressure that is mainly generated across the positive-pressure generating surface B and the indented surface C, respectively. In the above-mentioned inclination attitude, the magnetic element performs a read and/or write operation from and/or into the magnetic disk.
In the meantime, the magnetic head sliders M1, M2, and M3 shown in FIGS. 21 to 23 have the respective following problems.
In the magnetic head sliders M1 shown in FIG. 21, as described above, the positive-pressure generating surfaces B are divided into two parts in the width direction and have the step surface A1 formed therebetween. With this structure, at the moment when the magnetic head slider M1 is just levitated from the magnetic disk, air is likely to flow from and above the step surface A toward and above the step surface A1, whereby an extremely high positive pressure is unlikely to be generated.
Accordingly, although it is expected that the leading-side end surface S1 of the magnetic head sliders M1 is unlikely to be suddenly raised from the magnetic disk at the moment when the magnetic head slider M1 is just levitated from the magnetic disk. Since the positive-pressure generating surface B has a small area ratio, it is expected that a positive pressure generated across the positive-pressure generating surfaces B is unlikely to become high at the moment when the magnetic head slider is just levitated from the magnetic disk. Also, the magnetic head slider is unlikely to have a levitation attitude with which the trailing-side end surface St comes closer to the magnetic disk than the leading-side end surface S1. Accordingly, the distance between the magnetic element disposed close to the trailing-side end surface St and the magnetic disk cannot be made effectively smaller. Hence, a large spacing loss caused by the above structure does not allow a magnetic head apparatus capable of properly coping with the requirement of a higher recording density to be achieved.
In the magnetic head slider M2 shown in FIG. 22, since the positive-pressure generating surface B extends along the entire width of the slider (in the X direction indicated in the figure) without being divided into two parts, a high positive pressure is generated between the step surface A and the positive-pressure generating surface B at the moment when the magnetic head slider M2 is just levitated from the magnetic disk. Accordingly, the leading-side end surface S1 of the magnetic head slider M2 is more likely to be raised from the magnetic disk than that of the magnetic head slider M1 shown in FIG. 21.
As will subsequently be explained according to the results of simulation experiments, it has been found that the positive pressure during levitation becomes excessively high without appropriately setting the area ratio of the step surface A. Hence, the magnetic element disposed close to the trailing-side end surface St comes into contact with the surface of the magnetic disk at the moment when the magnetic head slider M2 is just levitated from the magnetic disk, thereby causing the magnetic element to be damaged.
In the magnetic head slider M3 shown in FIG. 23, the step surface A has a substantially wider area than the positive-pressure generating surface B. Hence, with the structure of the magnetic head slider M3 shown in FIG. 23, since a positive pressure generated between the step surface A and the positive-pressure generating surface B becomes excessively high, according to the results of the simulation experiments, which will be subsequently described, the leading-side end surface S1 of the magnetic head slider M3 is excessively raised at the moment when the magnetic head slider M3 is just levitated from the magnetic disk. Accordingly, the magnetic element disposed close to the trailing-side end surface St is likely to come into contact with the surface of the magnetic disk.
In other words, the magnetic head slider is preferably formed such that the trailing-side end surface St is raised from the magnetic disk to the extent to which the magnetic element does not come into contact with the surface of the magnetic disk at the moment when the magnetic head slider is just levitated from the magnetic disk. Also, the magnetic head slider is preferably formed such that, during complete levitation of magnetic head slider after the disk has reached at high speed rotation, the trailing-side end surface St having the magnetic element disposed close thereto is declined more downward than the leading-side end surface S1. Also, the magnetic head slider preferably has a levitation attitude with which the magnetic element comes closer to the magnetic disk so as to allow the distance (spacing) between the magnetic element and the surface of the magnetic disk to become smaller.
In order to maintain the above-mentioned preferable levitation attitude during levitation of the magnetic head slider, the proper shape of a part of the disk-facing surface of the magnetic head slider close to the trailing-side end surface St is essential. With the structure of the magnetic head slider, for example, shown in FIG. 23, in which the magnetic-element-forming surface E having a very wide area extends close to the trailing-side end surface St, and the indented surface C is interposed between the positive-pressure generating surface B and magnetic-element-forming surface E, a positive pressure generated across the magnetic-element-forming surface E will become excessively high. After the magnetic head slider M3 has been levitated, a part of the magnetic head slider M3 lying close to the trailing-side end surface St is likely to be raised so as to be away from the magnetic disk due to the positive pressure generated across the magnetic-element-forming surface E. This prevents the magnetic element from being positioned effectively close to the magnetic disk.
Also, with the magnetic head slider whose inclination attitude does not significantly vary due to a pressure change (a fluctuation of airflow) during levitation, a variance of the distance between the magnetic element and the surface of the magnetic disk can be made smaller. Accordingly, stable recording and playback characteristics can be maintained.